Improvement in harrow-teeth



UNITED STATES WILLIAM E. PLATT,

PATENT OEEIoE OF DAYTON, OHIO.

4 IMPROVEMENT IN HARROW-TEETH.

Specification forming part of Letters Patent No. 143,713, dated October 14, 1873 application iled November 16, 1872.

To allvwhofm it may concern:

Be it known that I, WILLIAM H. PLATT, of

Dayton, in the county of Montgomery and State of Ohio, have invented a new` and valuable Improvement in Harrow-Gutters, and I specification, and'to the letters and figures of *l reference marked thereon.'

Figure l of the drawings is a representation of an under view of my harrow-knife attached to the beam. Fig. 2 is a side view of the saine. Fig. 3 is a front view of my harrowknife. -Fig. 4 is a view of the plate from whichmy knife is struck up.. Figs. 5, 6, and 7 are sections. I

This invention has relation to harrowknives; and the novelty consists in the form of the knife, whereby it is especially adapted to the purpose in point of efliciency and durability. The object of this invention is to provide a knife-blade for a harrow which will remain rigidly upright in the position in which it is set, and whose edge, producing a draw-v ing downward cut, is of a sufficiently-hardy nature to withstand the rough service to which a harrow-knife is subjected for a considerable length of time.

These knives, as is well known, are usually arranged at intervals between' the teeth of `a harrow, and, while being'subjected to the uncertain oblique movement of this instrument, are depended upon to cut clods, overturned sods, sticks, and trash of all kinds 5 hence, it is important that they should be Vmade of the best steel, and of the form below described.

In the accompanying drawings, the letter A designates the blank from which thel knife Bis struck up and perforated in the iiange O, usually at one operation. This flange G'extends the entire length of the top of the blade, and is bent at right angles therewith, so that when it is secured by screws lor bolts passing through the perforations 'c c Vshown in the sectional views.

into the harrow-beam the blade will assume a rigidly-upright position. The side faces of the knife-blade are parallel, and the widest portion of the blade is next to the ilange. From this part the blade, bounded in front bya convex cutting-edge, b, and in rear by a concave edge, c, becomes gradually narrower,

-fmally terminating in an upright edge, d,

which connects the convex cutting-edge with the concave rear edge. The profile of the. convex cutting-edge is circular, and in length it is a quadrant or nearly so. By this form a drawing cutis secured regularly and constantly increasing in keenness from the heel of the blade to the point, as the sectional views sufliciently illustrate. make efiicient the very hardy edge of the blade. This hardiness is secured by placingl the edge in the middle plane of the blade, and connecting it with the faces of the blade by rapidly beveled and rounding surfaces, as is Thus the angle of the edge 4is made substantial, and at the same time the metal falls away from it sufficiently rapidly to prevent clogging, and in its lower or more horizontal parts the Obliquity of the edge to the horizontal draft gives a very keen and perfect action where efficiency is chiefly required, as in cutting the matte grass and trash lying at the bottoms of the overturned sods and clods.

What I claim as new, and desire to secure This drawing cut is necessary to 

